Erroneous experimental set up, results, and conclusions of some scientists had supported and strengthened the hypothesis. For example, the Englishman John Needham claimed that vital life is needed for the spontaneous generation of microbes. Proponents and opponents of spontaneous generation hypothesis debated a lot starting from the time Leeuwenhoek presented his discoveries s to the public until the time of Rudolf Virchow, who in challenged the spontaneous generation with his concept and definition of biogenesis.
This concept claims that living cells can arise only from preexisting living cells. Virchow defended this concept to the scientific community but he did not come up with a convincing experiment to back up his idea. Pasteur showed that microorganisms exist in the air and can contaminate sterile solutions, but he emphasized that air itself does not produce microbes.
He filled a number of short-necked flasks with beef broth and then boiled their contents. He immediately sealed the mouths of some of the flasks while he left the others open and allowed to cool. After few days, the contents of the unsealed flasks were found to be contaminated with microorganisms. No evidences of growing microorganisms were found on the sealed flasks.
This premise historically contrasted with the ancient belief in spontaneous generation, which held that certain inorganic substances, left alone, give rise to life such as bacteria, mice and maggots in a matter of days. The premise of biogenesis had been suspected long before being definitively demonstrated.
A demonstrative experiment, which showed biogenesis right down to the bacterial level, was devised by Louis Pasteur in Spontaneous generation is also known as Aristotelian abiogenesis, after its ancient Greek proponent. The stealth and invisibility of such organisms as flies, mice and bacteria allowed belief in spontaneous generation to hold sway for millennia.
Pioneering use of the still-new microscope in the 18th century began to erode its credibility; seeing fly eggs and bacteria under the microscope helped to demystify their nature. By Pasteur's time, experimentation had defended biogenesis at the macroscopic level. Only microscopic biogenesis was left to be proven.
In , Francesco Redi addressed the question of macroscopic spontaneous generation when he published the results of an experiment in which he placed rotting meat in a container and covered the container's opening with gauze. If the gauze was absent, maggots would grow on the meat.
If the gauze was present, maggots would not grow on the meat, but would appear on the gauze. Redi was observing flies depositing eggs as close to a food source as could be reached. A century later, an experiment performed by Lazzaro Spallanzani in indicated biogenesis on the microscopic level. Spallanzani wanted to avoid contamination by boiling a meat broth in a sealed container.
The problem with this approach was that air in the container could shatter the container upon heating. Therefore, he evacuated the container after sealing it closed. The broth did not subsequently cloud with bacterial growth, supporting the theory of biogenesis.
This went against the idea of descent through modification proposed by Charles Darwin. Franceso Redi in also did experiments proving that fly larva came only from flies.
Maggots were thought to occur spontaneously. Redi did controlled experiments that proved maggots did not come from dead meat spontaneously. These experiments disproved the theory of a biogenesis that life could come from non living things.
The experiments of Louis Pasteur and Redi established the theory of biogenesis, that complex organisms come only from complex organisms. Francesco Redi an italian physician and poet in He tried to disapproved this experiment but not able to.
But Louis Pasteur was the real one who disapproved the experiment. Which scientist proved biogenesis? David Drayer.
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